Published: December 30, 2011

TODOS SANTOS, Mexico — Clamshell containers on supermarket shelves in the United States may depict verdant fields, tangles of vines and ruby red tomatoes. But at this time of year, the tomatoes, peppers and basil certified as organic by the Agriculture Department often hail from the Mexican desert, and are nurtured with intensive irrigation.

Growers here on the Baja Peninsula, the epicenter of Mexico’s thriving new organic export sector, describe their toil amid the cactuses as “planting the beach.”